CN113474564A

CN113474564A - Improved plug-in magnetic meter and method

Info

Publication number: CN113474564A
Application number: CN202080014228.XA
Authority: CN
Inventors: W·S·瓦伦蒂纳; M·尤哈姆; K·霍勒; A·夏普德
Original assignee: Omnicom
Current assignee: Omnicom; Onicon Inc
Priority date: 2019-02-22
Filing date: 2020-02-21
Publication date: 2021-10-01
Also published as: WO2020172574A1; US20240085226A1; US20220307880A1; EP3927980A1; US20200271490A1; EP3927980A4; US11860011B2; MX2021008511A; CA3128391A1; US11378429B2

Abstract

A magnetic plug-in meter is disclosed herein. In some examples, the disclosed insertion meter includes a sensor head tube cylinder having a textured front surface and at least two electrodes. The disclosed insertion meter includes a textured front surface adapted to move a separation point of a fluid flowing through the sensor head tube toward the upstream surface as compared to an identical sensor head tube that does not include the textured front surface. Methods of measuring flow using example magnetic plug-in meters are also disclosed herein.

Description

Improved plug-in magnetic meter and method

Cross reference to related applications

This application claims priority to U.S. provisional application 62/809,252 filed on 22/2/2019, the entirety of which is incorporated herein by reference.

Technical Field

The present application relates to flow meters and more particularly to magnetic plug-in meters.

Background

The two most important characteristics of a precision flow meter are repeatability and linearity. Repeatability refers to the ability of a meter to obtain the same results under the same conditions. Linearity refers to the degree to which the output of the meter is linear with the flow delivered through the pipe or other conduit.

Without repeatability, it is difficult to make accurate meters. It is also difficult to calibrate and predict performance under various operating conditions (e.g., fluid, temperature, and tube type) if it is not linear. Plug-in flow meters are generally less accurate than in-line flow meters because plug-in flow meters have poorer repeatability and linearity than in-line flow meters. This is in part because plug-in flow meters, by the nature of their design, can only measure one point, or at least a small fraction, of the velocity profile, and this measurement must be correlated to estimate the average velocity of flow through the pipe. The shape of the velocity profile varies with flow, pressure and temperature, among other factors, which affect the conversion of the measurement at this point to the overall average velocity. On the other hand, inline meters measure across the entire velocity profile, enabling accurate direct measurement of the average velocity of the flow through the pipe. Thus, a plug-in magnetic meter may typically have an accuracy of +/-2% of the reading, while an inline meter has an accuracy as low as +/-0.2% of the reading.

However, plug-in meters have advantages when compared to in-line meters, because plug-in meters are modular and do not require a complete shutdown of the system for installation and maintenance. Furthermore, the plug-in meter is less costly and has a lower installation cost. To install an in-line meter, the system must be shut down, a section of pipe cut, flanges welded in place, and the meter installed between the two flanges. The plug-in meter may be mounted by a conventional ball valve.

Any advancement that can improve either the accuracy or repeatability of a plug-in meter is of great value.

Disclosure of Invention

In one aspect of the disclosure, a magnetic insertion meter is disclosed having a sensor head cylinder (cylinder) with a textured front surface and at least two electrodes. In another aspect of the present disclosure, a plug-in meter includes a field coil configured to emit an alternating magnetic field when excited with an alternating current. In yet another aspect of the present disclosure, the textured front surface is an upstream surface. In one aspect of the disclosure, the textured front surface is at least one of an abrasive, an impregnated abrasive, a deposited abrasive, and/or an abrasive layer (abrasive layer) on a substrate. In a particular aspect of the present disclosure, the textured front surface is sandpaper (sandpaper). In another aspect of the present disclosure, the textured front surface has a higher roughness than the material forming the sensor head tube.

In one aspect of the disclosure, the textured front surface includes at least one groove (grove). In another aspect of the present disclosure, the textured front surface includes two grooves extending along the longitudinal axis of the sensor head cylinder. In one aspect of the disclosure, the textured front surface includes dimples (dimples). In another aspect of the present disclosure, the plurality of dimples are equally spaced from each other. In another aspect of the present disclosure, the plurality of dimples form a pattern in which three of the plurality of gauges form an equilateral triangle. In one aspect of the disclosure, the textured front surface includes a plurality of rows of dimples. In one aspect of the present disclosure, the textured front surface comprises from about 3 columns of dimples to about 7 columns of dimples. In another aspect of the present disclosure, the textured front surface includes dimples. In yet another aspect of the present disclosure, the textured front surface is adapted to alter a boundary layer of a fluid flowing through the sensor head tube as compared to the same sensor head tube that does not contain the textured front surface. In another aspect of the present disclosure, the textured front surface is adapted to move a separation point (separation point) of a fluid flowing through the sensor head tube toward the front surface as compared to the same sensor head tube that does not contain the textured front surface. In one aspect of the present disclosure, the textured surface is a surface contour (surface contour).

In one aspect of the disclosure, a method of measuring flow is disclosed, wherein the method includes providing a magnetic insertion meter including a sensor head cylinder having a textured front surface and at least two electrodes and measuring outputs of the electrodes. In another aspect of the present disclosure, the textured front surface is at least one of an abrasive, an impregnated abrasive, a deposited abrasive, and/or an abrasive layer on the substrate. In another aspect of the present disclosure, the textured front surface includes at least one of dimples and/or grooves.

Drawings

FIG. 1 is a schematic view of an example plug-in meter.

Fig. 2, 3, 4, and 5 are views similar to fig. 1 depicting example flow conditions.

FIG. 6 is a graph depicting a meter factor for the meter of FIG. 1.

FIG. 7 is a schematic view of an example plug-in meter, according to disclosed embodiments.

FIG. 8 is a graph depicting a gauge factor for the gauge of FIG. 6.

FIG. 9 is a schematic view of an example plug-in meter, according to disclosed embodiments.

FIG. 10 is a perspective view of an example plug-in meter according to disclosed embodiments.

Fig. 11 and 12 show flow velocity flow models of the plug-in meters of fig. 1 and 10, respectively.

FIG. 13 is a graph depicting a meter factor for a plug-in meter in accordance with the disclosed embodiments.

Detailed Description

Fig. 1 shows a cross-section of a plug-in meter 100, the plug-in meter 100 having a cylindrical shape, looking down the longitudinal path (longitudinal access) of the example plug-in meter 100. An example plug-in meter 100 may be part of an example Sensor Assembly described in U.S. application 16/233,915, entitled "Scalable monomeric Sensor Assembly, Controller, and Methods of Making and Installing Same," filed on 27.12.2018, and published as US2019/0204129, which is incorporated herein by reference in its entirety as appendix A. The cross-section is taken at electrode 110.

The plug-in meter 100 includes a cylindrical sensor head tube 140 that is inserted into a tube carrying a suitable conductive fluid 180. In operation, the plug-in meter 100 generates a magnetic field using a field coil excited by an alternating current. According to faraday's law, a conductor (i.e., a conductive fluid) passing through the magnetic field induces an electrical potential and current that is indicative of the flow velocity. The insertion meter 100 measures the electrical potential (voltage or "V") generated by the flow velocity between at least two electrodes. For example, such a potential difference may be measured between at least one top electrode and at least one bottom electrode.

For example, the plug-in meter 100 may have 2 or more electrodes distributed from the top to the bottom of the longitudinal axis of the plug-in meter 100. In one particular example, the plug-in meter 100 may include one or more top electrodes, one or more bottom electrodes, and one or more center electrodes. The center electrode serves as an electrical reference, while the voltage potential is sampled between the paired top and bottom electrodes. The two electrodes 110 shown in fig. 1 share the same longitudinal height. Thus, the electrodes 110 may each be a top electrode, a bottom electrode, or a reference electrode. The electrodes 110 shown in fig. 1 may be electrically connected to form a single electrode, or they may be electrically isolated from each other to form two separate electrodes. In an example stand-alone configuration where the electrodes 110 are bottom electrodes, a first potential may be measured between one of the electrodes 110 and the corresponding top electrode, and a second potential may be measured between the other electrode 110 and a different top electrode.

Repeatability of fluid flow around previous plug-in meters 100 may be improved. FIG. 2 shows the meter 100 inserted in a flowing fluid 180 at an example velocity in the direction of arrow 182. For example, if the flowing fluid 180 at arrow 182 represents turbulent bulk (bulk) fluid. As shown, when the fluid contacts the front surface 120, the flowing fluid reaches a stagnation point 186, where the fluid flow is minimal. When the fluid 180 contacts the front surface 120 facing the oncoming fluid flow, the fluid 180 also forms a laminar boundary layer 184 (or boundary layer 184), which is the transition between the stagnation point and the bulk end flow 182. The forward surface 120 (i.e., the surface facing the oncoming fluid flow) will also be referred to herein as the upstream surface. It should be noted that if the fluid flows in the opposite direction, the opposite surface will become the upstream surface. As boundary layer 184 flows toward rear portion 122 (or, a downstream surface) of plug-in meter 100, boundary layer 184 becomes unstable or otherwise transitions away from the surface of plug-in meter 100. This boundary layer transition is indicated as separation point 105.

The location of the separation point 105 is not consistent because the fluid flow is chaotic and it is affected by changes in the amount of fluid flow across the meter 100 as well as fluid properties such as the velocity, temperature, viscosity, density of the fluid and surface finish of the cylinder. Further, the location of the separation point 105 may also vary based on whether the flow rate is increasing or decreasing to a given speed. Fig. 3 to 5 show three different velocities of the same fluid in increasing order, i.e. the fluid velocity of fig. 5 is higher than the fluid velocity of fig. 4, and the fluid velocity of fig. 4 is higher than the fluid velocity of fig. 3. In fig. 3, the separation point 105a is typically located between the electrode 110 and the rear portion 122. In fig. 4, the velocity of the fluid is greater than that of fig. 3 and less than that of fig. 5, and the separation point 105b has shifted to the vicinity of the electrode 110. In fig. 5, the velocity of the fluid is greater than the velocity of the fluid of fig. 3 and 4, and separation point 105c has shifted closer to front 120 of insertion meter 100, i.e., closer to the direction from which the fluid flow came. While not being bound by theory, it is believed that this non-uniformity in the location of the boundary layer/separation points 105(105a, 105b, 105c) contributes to the degradation in linearity and repeatability experienced by previous plug-in meters. That is, an unstable boundary layer at the sensor electrode 110 may hinder accurate and repeatable results compared to a more stable boundary layer. For example, based on non-uniformities in fluid flow or changes in flow rate, under some conditions the separation point 105a may be closer to the electrode 110 (whether downstream or upstream), which under the right conditions may result in more variation in the measurements made at the electrode 105 a. Although the separation point 105c of FIG. 5 has been offset toward the front surface 120, the change in boundary layer shown between FIG. 3 and FIG. 5 may cause the plug-in meter 100 to deviate from the calibration state.

FIG. 6 shows an example meter output (1P-round 1 to 1P-round 5) of an example plug-in meter 100 (FIG. 1) as a graph of meter factor (expressed as (LPIP pulse/Ioil Gal)) versus nominal flow rate (expressed in feet per second (ft/s)). The meter factor (or correction factor) is typically dimensionless and is calculated as the ratio between the meter output and a value determined by a standard reference meter, such as a plug-in meter pulse/reference (Ref) meter pulse. This can be calculated from rate measurements or quantity measurements. The different traces show repeated test runs of the same plug-in meter 100 under the same conditions. The results show that both repeatability and linearity can be improved. For the test case shown in FIG. 6, the best accuracy achievable using a constant gauge factor would be +/-3% of the reading. For reference, an ideal sensor will produce a constant meter factor (horizontal line) regardless of the flow rate being measured, which means that the meter output is linear with flow, and can be easily corrected by multiplying the meter output by the constant meter factor. While an ideal meter is likely to be impossible, linearity of the meter factor is desirable. Linearity simplifies calibration, i.e., fitting the meter reading to a two-point line is simpler than fitting a complex curve (e.g., a complex curve as in fig. 6) which requires multiple characterizations. Linearity also simplifies calibration for other operating conditions, improves reproducibility among multiple meters (cell-to-cell variation), shortens manufacturing verification cycles to confirm meter accuracy, and limits the need to test multiple meter cells to determine a characteristic curve (i.e., fewer cells are needed to characterize multiple tubes/dimensions). If the gauge factor is constant, it can be assumed that although the value may change, it will be constant for other fluid or flow conditions. If the relationship is linear, it is much easier to determine corrections for other flow conditions and fluids.

Previous attempts have been made to change the arrangement of electrodes by rotating each electrode toward the back of the meter, i.e., away from the front 120 of the plug-in meter 100, to improve reproducibility. This places the electrodes within the laminar boundary layer before the laminar boundary layer transitions to the turbulent boundary layer. While this may (hypothetically) mitigate some of the effects of an unstable boundary layer by forcing a consistent velocity profile, it will also result in a reduction in the sensor signal, which is disadvantageous because it reduces the signal-to-noise ratio.

Fig. 7 shows a plug-in meter 200 with electrodes 210. Plug-in meter 200 and electrode 210 are identical to plug-in meter 100 and electrode 110, respectively, except that plug-in meter 200 includes a textured surface 230 on a front 220 of plug-in meter 200. While the specific configuration of the textured surface 230 may vary based on the particular operating conditions of the plug-in meter (e.g., meter circumference, tube diameter, tube flow rate, fluid type, fluid velocity, fluid density, etc.), the textured surface 230 should be sufficiently textured to trigger or manipulate the boundary layer such that the point of separation (see, e.g., 105, fig. 2) always occurs consistently in the forward direction of the electrode 210 (toward the front 220 of the plug-in meter 200, i.e., toward the source of flow) for normal operating conditions (and preferably all operating conditions) of the corresponding plug-in meter. In the illustrated embodiment, the textured surface 230 should be rougher than the rest of the sensor head tube 240 of the insertion meter 200. For example, in one example, the textured surface 230 is rougher than the material (e.g., smooth plastic and metal) forming the sensor head tube.

As shown in fig. 7, the textured surface 230 may be, for example, sandpaper or other similar abrasive that adheres to the substrate of the sensor head tube 240. Example abrasives on the substrate include, for example, sand, glass, alumina, silicon carbide, abrasive cloth, pumice, fine abrasive cloth, and the like. While the present application discusses the use of paper as the substrate, other flexible substrates (e.g., cloth, adhesive, or polymer) as well as curved, non-flexible substrates formed or machined into the outer circumference of the sensor head tube 240 may also be used. In addition, the abrasive can also be impregnated or deposited into or onto a surface as an abrasive layer without a substrate. In one example, the textured surface 230 may extend the length of the sensor head tube 240 or be applied locally in the area near the electrode 210. The amount of texturing will depend on the type of material used, the size and shape of the insert meter and flow tube, and the characteristics of the fluid, but nevertheless should be sufficiently textured to manipulate the boundary layer as discussed above.

For example, the textured surface 230 of sandpaper may comprise 40-80 grit adhesive tape having a base thickness of about 0.030 inches and a width (inclusive) of about 0.360 inches to about 0.400 inches, the width being the dimension around the circumference of the sensor head tube 240. In one example, the textured surface of the sandpaper is applied centered at the stagnation point and along the entire length of the meter (or, effectively, along the entire length of the sensing portion of the meter sensor head tube 240).

FIG. 8 shows a plot of example meter output (sand 1-run 1-90 degrees to sand 1-run 3-90 degrees) of an example plug-in meter 200 (FIG. 7) as a meter factor (expressed as meter pulses/reference meter pulses) versus a nominal flow rate (expressed in feet per second (ft/s)). The different traces show repeated test runs of the same plug-in meter 200 under the same conditions. As shown, both repeatability and linearity are improved compared to the plug-in meter 100 (fig. 1). The improved linearity simplifies calibration and improves performance in different tubes and fluids.

In an alternative example, instead of adding a textured substrate to the surface of the insertion meter sensor head tube, the texture is formed directly on the outer surface of the sensor head tube. FIG. 9 shows an example embodiment of an insertion meter 300 having electrodes 310. The plug-in meter 300 and the electrode 310 are identical to the plug-in meter 200 and the electrode 210, respectively, except that the textured surface of the plug-in meter 300 includes two longitudinal notches 330 or grooves in a sensor head tube 340 located on the front 320 of the plug-in meter 300. The notch 330 extends between the electrodes 310 along the longitudinal axis of the plug-in meter 300. The notch 330 is also used to manipulate the boundary layer, as discussed above with respect to the plug-in meter 200.

In yet another embodiment, the textured surface comprises an array of dimples, such as the type of dimples found in a typical golf ball. For example, the textured surface may include a plurality of rows of dimples. In one example, the textured surface includes about 3 columns of pits to about 7 columns of pits. In another example, the textured surface includes more than 7 columns of pits. The specific textured surface features discussed above may also be combined. For example, the textured surface may include longitudinal grooves and rows of pits. Fig. 10 shows a plug-in meter 400 of similar configuration to plug-in

meters

300, 200, and 100, including, for example, having a plurality of electrodes including two top electrodes 410, two center or reference electrodes 411, and two bottom electrodes 412. However, as shown, the textured surface of the insertion meter 400 includes a dimple 430 formed on or within the sensor head tube 440. The pockets 430 of the plug-in meter 400 include 3 columns of pockets, with a center column 432 longitudinally offset from the outer two columns 434 of pockets 430, which results in a pattern of one by two count rows (i.e., alternating between 1 pocket and 2 pocket rows). In one example, adjacent dimples 430 form an equilateral triangle such that the gap between any two dimples 430 remains uniform. The recess 430 extends the longitudinal length of the sensor head tube beyond the top electrode 410 and the bottom electrode 412 in both directions.

The dimples 430 may be formed as additional surfaces added to the sensor head tube 440, or may be formed within the sensor head tube 440 by, for example, milling or during the formation of the sensor head tube 440 itself. Although the size and configuration of each dimple can be manipulated according to the particular sensor installation, as shown in FIG. 10 as one example, each dimple 140 has a 0.020 "deep cut of approximately 0.125" radius into the sensor head tube 440 using an 1/4 "ball nose end mill. There is a gap of about 0.20 inches between adjacent dimples. Further, the arc length between each hole in a particular row (i.e., a dimple in one outer row 434 to a dimple in another outer row 434 on the same radial plane) is about 35 degrees to about 36 degrees (inclusive), or specifically about 35.35 degrees as shown. Although only a pocket 430 partially surrounding the sensor head tube 440 is shown in fig. 10, in alternative examples, the pocket 430 may more completely surround or even completely surround the sensor head tube 440.

FIGS. 11 and 12 are flow velocity flow models comparing insertion sensor 100 (FIG. 1) and insertion sensor 400 (FIG. 10) under the same flow conditions. In each of fig. 11 and 12, the scale has been normalized to 130 inches/second. As shown, the separation point 110 is closer to the electrode 105 than the separation point 405 and the electrode 410.

Fig. 13 shows the increase in linearity of a plug-in meter with 7 rows of pits (shown as unfilled purple dots) compared to a smooth previous meter (shown as filled blue dots). The graph shows the ability to extend linearity to within +/-1.5% of the reading with a nominal flow rate as low as 1 foot/second using an example plug-in flow meter with seven columns of dimples 430.

In another example embodiment, the cross-sectional shape of the plug-in meter is altered to affect the boundary layer/electrode interaction. For example, the cross-section of the insertion meter may be formed as an oval or tear-drop shape to improve linearity and repeatability. In such embodiments, the textured surface itself is a surface profile.

Also disclosed herein is a method of measuring flow within a pipe or conduit. The method includes providing a magnetic insertion meter including a sensor head cylinder having a textured front surface and at least two electrodes. Such plug-in meters may be, for example, those discussed above with reference to fig. 7-9 and alternative embodiments thereof. In one example embodiment, the method includes measuring an output of the electrode.

It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

Appendix A

(19) United states of America

(12) Patent application publication Ball et al

(10) Publication No.: US2019/0204129A1

(43) The publication date is as follows: 7 month and 4 days 2019

(54) Scalable monolithic sensor assembly, controller and methods of making and installing same

(71) The applicant: ornikang, Largo, FL (US)

(72) The inventor: eric Ball, Largo, fl (us); adam Tyler, Largo, fl (us); kevin Holler, Largo, FL (US); darral Ying, Largo, fl (us); david gagliardio, Largo, fl (us); michael Upham, Largo, fl (us); adam Sheppard, Largo, FL (US)

(21) Application No.: 16/233915

(22) Day of delivery: 12 month and 27 days 2018

Data of related U.S. applications

(60) Provisional application No. 62/611,251 filed on 28.12.2017

Open classification number

(51) International classification number G01F 1/58(2006.01)

(52) American classification number CPC G01F 1/588(2013.01)

(57) Abstract

Scalable monolithic sensor assemblies, controllers, and methods of making and installing the same are disclosed. The sensor assembly includes a sensor head sized to completely traverse the diameter of the pipe such that its electrodes sample voltage across the entire pipe flow indicative of the diameter of the pipe flow. Including an improved stem design that reduces insertion forces and increases lateral stability of the sensor head. An improved insertion device is disclosed that provides independent axial insertion and rotation. An improved core is disclosed that minimizes magnetic field disturbances and reduces manufacturing costs. An improved controller with improved sensitivity is disclosed.

Scalable monolithic sensor assembly, controller and methods of making and installing same

RELATED APPLICATIONS

This application claims priority to U.S. provisional application 62/611,251 filed on 28.12.2017, the entirety of which is incorporated herein by reference.

Background

The disclosed embodiments relate generally to electromagnetic flow meters.

Current plug-in flow meters sample a small area of flow through a pipe. Even those designed for large pipes, only a few small cross sections are sampled. They then average these readings in an attempt to obtain accurate flow measurements. All averages have some weighting; most often each reading is given equal weight. Unfortunately, if the flow changes with respect to the flow for the calibration meter, then even if positioned so that each sensor has an equal annular area, giving each sensor an equal grade does not result in an accurate measurement. Giving unequal weights can result in accurate readings, but detailed information about the flow patterns is required to give these weights. If the flow changes, the meter will not be accurate. Separate cores require multiple preamplifiers. This results in a bulky and expensive meter.

Current plug-in flow meters also utilize threaded connections in the body of the meter. Threaded joints risk rotation and back-out after installation. Using a threaded joint as part of an electromagnetic sensor head is challenging because the sensor must remain aligned after installation and cannot be allowed to rotate. The snap fit prevents axial movement rather than rotation. They are not strong when bent.

Furthermore, conventional plug-in meters trade off two factors in pole design: insertion force and flexural strength. The smaller the rod, the less force is required to mount the meter. However, thin rods are subject to undesirable flexing, vibration, fatigue and breakage.

Further, the electrode wires in current plug-in meters need to be shielded from the electromagnetic field of their cores. A typical core accomplishes this by running the electrode wires along the middle of the core where no field is generated. This can make the machine expensive, difficult to install, and increase the complexity of the coil winding.

A plug-in flow meter is installed into the flow tube using a hot tap adapter mounted to a ball valve. As a result, conventional hot tap adapters anchor the meter at the top of the adapter after installation. This is the point furthest from the force of the flow and the longest moment arm. This causes excessive deflection and vibration that negatively affects the accuracy of the meter.

Hand-insertable hot-severable plug-in flow meters often have their alignment disengaged from their mounting. That is, the meter may be screwed onto the valve fitting and then aligned afterwards. However, mechanically assisted thermally severable joint flow meters are typically locked in the orientation in which they are installed. Screwing the meter onto the valve fitting determines the angle of the meter with respect to the flow. This means that the installer must often trade off between the correct mounting torque of the fitting and the correct angle of the meter with respect to the flow.

The accuracy of plug-in flow meters also depends on how consistently they are installed. Any difference in the mounting angle between the position where the meter is calibrated and the position where the meter is mounted will degrade the accuracy of the meter.

The current plug-in flow meter controller must compensate for the DC bias on the electrodes, which may be caused, for example, by the electrochemical interaction of the electrodes. This reduces the accuracy of the meter. In addition, other plug-in flow meters require precise timing and switching circuitry to read the signal, adding to the overall complexity and cost of the meter.

Drawings

FIG. 1 illustrates a perspective view of an example sensor assembly in accordance with the disclosed embodiments;

FIG. 2 illustrates the sensor assembly of FIG. 1 as viewed in the system flow direction in accordance with the disclosed embodiments.

FIG. 3 illustrates a cross-sectional view of FIG. 2 along section line III-III in accordance with disclosed embodiments.

FIG. 4 illustrates a cross-sectional view of FIG. 3 along section line IV-IV, in accordance with disclosed embodiments.

FIG. 5 illustrates a cross-sectional view of FIG. 4 along section line V-V in accordance with the disclosed embodiments.

FIG. 6 illustrates a detailed view of detail 6 of FIG. 4, in accordance with disclosed embodiments.

FIG. 7 illustrates a detailed view of detail 7 of FIG. 4, in accordance with disclosed embodiments.

FIG. 8 illustrates a perspective view of an example sensor head without an example sensor head tube in accordance with the disclosed embodiments.

FIG. 9 illustrates a side view of an example sensor head without an example sensor head tube in accordance with the disclosed embodiments.

FIG. 10 illustrates a front view of an example sensor head without an example sensor head tube, in accordance with disclosed embodiments.

FIG. 11 illustrates a detailed view of detail 11 of FIG. 8, in accordance with disclosed embodiments.

FIG. 12 illustrates a schematic view of an example sensor head and stem during assembly in accordance with the disclosed embodiments.

FIG. 13 is a cross-sectional view of FIG. 12 along section line XII-XII, in accordance with a disclosed embodiment.

FIG. 14 is a schematic view of a sensor head tube and stem according to a disclosed embodiment.

FIG. 15 illustrates a schematic view of an example sensor head and a stem after connecting the example sensor head and the stem together, in accordance with the disclosed embodiments.

Fig. 16 is a cross-sectional view along section line XVI-XVI of fig. 17, in accordance with the disclosed embodiment.

Fig. 17 shows a schematic view of an example anchor prior to insertion into an example sensor head, in accordance with disclosed embodiments.

FIG. 18 is a cross-sectional view of FIG. 17 along section line XVIII-XVIII, in accordance with the disclosed embodiments.

FIG. 19 is a cross-sectional view of FIG. 19 along section line XIX-XIX in accordance with a disclosed embodiment.

Fig. 20 and 21 illustrate an example sensor assembly in two stages of installation in accordance with a disclosed embodiment.

Fig. 22 illustrates a perspective view of an example mechanical insertion device 260, in accordance with the disclosed embodiments.

Fig. 23 illustrates a front schematic view of an example mechanical insertion device 260, in accordance with the disclosed embodiments.

Fig. 24 illustrates a front schematic view of an example mechanical insertion device in accordance with the disclosed embodiments.

FIG. 25 illustrates a schematic perspective view of an example controller and light emitting wires, according to the disclosed embodiments.

FIG. 26 illustrates a schematic top view of FIG. 25 in accordance with the disclosed embodiments.

FIG. 27 illustrates a schematic front view of FIG. 25 in accordance with disclosed embodiments.

FIG. 28 illustrates a magnetic field density diagram for an example coil and an example core in accordance with the disclosed embodiments.

Fig. 29A and 29B show electrical schematic block diagrams of a controller and a sensor head according to the disclosed embodiments.

FIG. 30 illustrates a method in accordance with the disclosed embodiments; and;

FIG. 31 illustrates the sensor assembly of FIG. 1 together with the mechanical insertion device of FIG. 24 when viewed in the system flow direction, in accordance with the disclosed embodiments.

Detailed Description

FIG. 1 illustrates an overall perspective view of an example sensor assembly 101 mounted above and within a flow tube 170. It should be noted that only a portion of the flow tube 170 is shown in its entirety. Other portions of the flow tube 170 are shown in phantom for clarity. The flow tube 170 is a section of a system (typically a commercial or industrial system) in which a system designer or customer desires to measure the system flow 172 (rate or volume or mass flow). The flow tube 170 may be any size diameter tube. The sensor assembly 101 will be appropriately telescoped for the tube dimensions so that the sensor head 100 and associated components (discussed below) traverse the entire inner diameter of the tube. Typical use in the industry is typical for pipes having diameters between one inch and 24 inches, although the disclosed embodiments are equally applicable to pipes up to 80 inches and larger. Many industrial and commercial systems utilize 6-12 inch tubing that is equally compatible with the sensor assembly 101. The example sensor assembly 101 is particularly advantageous for pipes having dimensions in excess of six inches, where prior sensors relied more on the assumption of fluid flow within the pipe.

Example systems include, but are not limited to, chillers, HVAC (heating, ventilation, and air conditioning), food processing, water treatment, water distribution, gas, agricultural, chemical refining and processing, and liquid, slurry, petrochemical, and pharmaceutical systems. For the remainder of this description, we will refer to "fluid" as meaning any fluid or fluid-like material that is capable of inducing an electrical current when passed through a magnetic field. The sensor assembly 101 can be used with other fluids and systems provided that the fluid has sufficient conductivity to induce a current when flowing through a magnetic field. Most water-based fluids include this characteristic. The system flow 172 within the flow tube 170 is generally parallel to the tube and perpendicular to the longitudinal path of the sensor assembly. As described below, the relative motion between the system flow 172 and the stationary sensor assembly 101 generates electrical signals that are then converted into flow velocities or volumetric or mass flows.

The sensor assembly includes a sensor head 100, the sensor head 100 generating a magnetic field and measuring an electrical potential (voltage or "V") produced by the flow velocity at least one top electrode and at least one bottom electrode, as will be discussed below. The voltage is electrically carried to a controller 300 mounted outside of the flow tube 170. The internal construction and function of the sensor head 100 will be discussed in more detail below.

Typically attached to the flow tube 170 at installation of the system is the valve 120. The valve 120 and flow tube 170 can have a short section 171 of intermediate tube, which short section 171 of intermediate tube can be part of the flow tube 170 or attached to the flow tube 170. However, such a segment 171 will only affect the overall length required for the disclosed sensor assembly 101, which sensor assembly 101 can be easily scaled depending on the application. As such, this paragraph will not be discussed further. Valve 120 (typically a ball valve) has sufficient direct path through its center when opened to allow sensor head 100 to be inserted through valve 120 during installation of the sensor assembly. The valve 120 has an axis 114 at the center of the valve 120, and the axis 114 is perpendicular to the flow tube 170 and the system flow 172. The accuracy of the sensor head 100 and the resulting flow velocity depends on the extent to which the longitudinal axis of the sensor head 100 is perpendicular to the system flow 172. Also, because the sensor head 100 is inserted through the valve 120 (discussed below) during installation, the longitudinal axis of the sensor head 100, when aligned, should coincide with the axis 114. As will be discussed below, the alignment features in the example sensor assembly 101 have improvements over previously known sensors.

Prior to installation, the sensor head 100 is retracted within the thermal tap adapter 130. When installed, hot tap adapter 130 is connected to valve 120. The hot tap adapter 130 may be removably connected by, for example, a threaded connection between the valve 120 and the hot tap adapter 130, or in the alternative, the hot tap adapter 130 may be fixedly connected via pressing, welding, or the like. The sensor head 100 is attached to a wand, discussed further below, that extends through the thermal tap adapter 130 to a mechanical insertion device 260, also discussed further below. After the thermal tap adapter 130 is connected to the valve 120, the valve 120 is opened and the sensor head is inserted into the flow tube 170 until the sensor head bottoms out. Further details regarding installation will be discussed below.

Fig. 2 shows the sensor assembly of fig. 1 as viewed in the direction of system flow 172. In the top, bottom and middle regions of the sensor head 100 are holes in which the

electrodes

105, 106, 107, 108, 109, 110 protrude slightly to contact the fluid flow in the flow tube 170. As shown, there is a left top electrode 105, a right top electrode 106, a left bottom electrode 107, a right bottom electrode 108, a left center electrode 109, and a right center electrode 110. The center electrodes 109, 110 serve as ground or reference electrodes. When a flow measurement is made, a potential measurement (voltage) is made between the corresponding top and bottom electrodes. For example, to measure the left portion of the sensor head 100, a voltage measurement is made across the top left electrode 105 and the bottom left electrode 107. To measure the right portion of the sensor head, a voltage measurement is made across the top right electrode 106 and the bottom right electrode 108. In another configuration, the top electrodes 105, 106 and the bottom electrodes 107, 108 are each separately electrically connected such that separate measurements are made, i.e., between the top and bottom electrodes.

This arrangement of electrodes results in only two measurement depths at the top and bottom of sensor head 100, i.e., near or adjacent to inner surfaces 173 (on opposite sides of flow tube 170) of flow 170, respectively. Note that the top electrodes 105, 106 and bottom electrodes 107, 108 span the diameter of the flow tube 170. That is, the top electrodes 105, 106 and the bottom electrodes 107, 108 are adjacent to the radially opposite inner surfaces 173 of the flow tube 170. Measuring the potential between two measurement depths across the diameter of the flow tube 170 results in improved accuracy compared to measuring multiple sections of the tube as done in previous sensors and then averaging the measurements together. Extending the distance between the electrodes also increases the voltage potential and improves meter performance. All fluid in the sensing region will be included in the voltage potential integral and will contribute to the meter reading. The larger the area, the more fluid is included and the more accurate the meter. Previously known sensors use less than 10% of the (stretch) large tube diameter. The inclusion of a large sampling area in the example sensor head 100 allows for high performance in areas of varying flow patterns. Although the regions of high and low speed may be offset, they will still contribute to the overall voltage regardless of their location because they are all included in a single integral. Because there are only two measurement depths, the sensor head 100 can easily scale to any size tube without having to readjust the electrode spacing and remove the wired connection between the electrodes and the signal conditioning circuitry, as compared to other sensors that must average several voltage measurements across the tube diameter together.

Fig. 3 shows a cross-sectional view along the cross-sectional line III-III of fig. 2. It is noted that although section line III-III appears centrally, i.e., along the shaft 114, it is offset such that fig. 3 shows only certain components in the section, as will be clear from the remaining disclosure. The sensor head 100 is attached to the large diameter pole 132 at the pole cap 136. The large diameter rod transitions to a small diameter rod 134. The rods (including the large diameter rod 132 and the small diameter rod 134) may be formed as a single piece, or may be formed as several pieces and then joined together using known machining methods. The rod may be formed of, for example, stainless steel or other types of steel or steel alloys (e.g., 316 stainless steel). However, any material having sufficient strength for installation and under the operating conditions of the system is suitable. Supporting the large diameter pole 132 and the small diameter pole 134 is an anchor 140, which will be discussed further below.

The small diameter stem 134 protrudes from the top of the hot tap adapter 130 and passes through a top sealing cap 252. A top sealing cap 252 seals the system pressure from escaping to the atmosphere and seals against the small diameter rod 134 with an O-ring or seal 254. The top sealing cap 252 may be secured with threads, pressing or welding or other mechanical means sufficient to withstand the system pressure of the hot tap adapter 130. The small diameter rod 134 also protrudes through a collar 150, a spring or springs 152, and an upper adjustment plate 154, each of which will be discussed further below. The bottom of the sensor head tube is sealed with a bottom sealing cap 192.

Fig. 4 shows a cross-sectional view along section line IVI-IV of fig. 3. The sensor head 100 includes one or more field coils 180, for example made of copper wire, wrapped around a core 104. Other conductive materials sufficient to conduct field coil current may also be used for field coil 180. The field coil 180 is wound to conform to the system flow 172 (fig. 1), that is, the area inside the field coil is substantially parallel to the system flow 172. As shown in fig. 4, a cross-section of field coil 180 shows lines going in and out of the page at the top and bottom of core 104. The field coils 180 and the core 104 are within the sensor head tube 102 for protecting internal components. The sensor head tube 102 may be made of any easily machinable material that can withstand the system temperature and pressure, including plastics and metals. In one example, the sensor head tube comprises an acetal polymer. The head tube 102 may also be overmolded over the coil 180 and the

electrodes

105, 106, 107, 108, 109, 110. When the field coil 180 is excited with an Alternating Current (AC), an alternating magnetic field is generated (see, for example, fig. 28 showing the magnetic field density). The conductive fluid flows through the magnetic field in the direction of system flow 172 (fig. 1). According to Faraday's law, a conductor (i.e., a conductive fluid) passing through a magnetic field induces an electrical potential and current indicative of the velocity of the flow. Voltages are measured between the top electrodes 105, 106 and the bottom electrodes 107, 108, respectively, to determine the flow rate of the liquid.

Fig. 5 shows a cross-sectional view along section line V-V of fig. 4. As shown, the field coil is wound around and along a longitudinal axis 114 of the (down) core 104. The reference electrodes 109, 110 protrude through the sensor head tube 102. The sensor head tube 102 may be sealed around the electrodes 109, 110 with O-rings/seals 111. The electrodes may be friction fit within the bore of the sensor head tube 102 or may be secured with fasteners, adhesives, or other known methods. Electrode wires 112 extend from the top of the sensor head 100 within the sensor head tube 102 to each of the electrodes 109, 110, respectively. It is noted that for simplicity the electrode wire 112 is shown as a single cable, however, it should be noted that a single cable may comprise separate insulated conductors within the cable, or the cable may be replaced by a separate insulated conductor. The top electrodes 105, 106 and bottom electrodes 107, 108 have the same configuration as the electrodes 109, 110, may also be sealed with O-rings/seals 111, and also have electrode wires 112. The electrode wire 112 is routed in a channel 350, discussed below with reference to fig. 28. The electrode wire 112 may be held near the center of the core 104 with a spacer 116. The spacer may be any material that is sufficiently rigid to hold the electrode wire 112 in place. Preferably, the spacer 116 is an insulating material made of plastic such as ABS (acrylonitrile butadiene styrene) or nylon. The electrode line 112 extends through the spacer 116 and is electrically connected to the

electrodes

105, 106, 107, 108, 109, 110, which are not shown for simplicity. The electrode wire 112 may extend through a hole in the spacer 116 or through a gap 118 between the spacer 116 sections or through a formed channel. In another example, the individual wires are replaced by circuit traces on a Printed Circuit Board (PCB) or any other known method of electrically connecting electrodes, which are placed with the channels 350 and/or secured to the core. The electrode wire 112, along with electrical connections (not shown) for the field coils 180, extends up through the large diameter pole 132 and the small diameter pole 134 to the controller 300 (fig. 1).

Fig. 6 shows a detailed view of detail 6 of fig. 4. A detailed view of the top electrodes 105, 106, O-ring/seal 111, spacer 116 and gap 118 is shown in this view. Also shown is a stem cap 136 attached to the lower portion of the large diameter stem 132. The stem cap 136 forms a threaded and snap-fit 200 connection with the sensor head tube 102, as will be discussed further below.

Fig. 7 shows a detailed view of detail 7 of fig. 4. The bottom of the sensor head tube 102 is sealed with a bottom sealing cap 192 and an O-ring/seal 255. The resilient leg 190 is on the bottom of the bottom sealing cap 192, and the resilient leg 190 and the bottom sealing cap 192 are fastened together by a screw 194. A gasket (not shown) may also be included to distribute the force. The resilient feet provide a friction-increasing surface to better secure the sensor head 100 to the inner surface 173 of the flow tube 170 (e.g., to prevent rotation), and may also provide protection for the sensor head 100 and the flow tube 170 during installation and adjustment. Also shown are bottom electrodes 107, 108, O-rings/seals 111 and spacers 116.

Fig. 8-10 show perspective, side, and front views of the sensor head 100 without the sensor head tube 102. Fig. 11 shows a detailed view of detail 11 of fig. 8. The field coils are wound to conform to the system flow 172, while the

electrodes

105, 106, 107, 108, 109, 110 protrude perpendicular to the system flow 172.

Referring now to fig. 12-16, the connection between the large diameter stem 132 and the sensor head tube 102 will be discussed. Fig. 13 is a cross-sectional view along section line XIII-XIII of fig. 12, and fig. 16 is a cross-sectional view along section line XVI-XVI of fig. 15. The end of the large diameter rod 132 has both a shaft threaded portion 202, a lug 204, and an O-ring/seal. It is noted that fig. 12-16 and others show the shaft threaded portion 202 and the lug 204 on a separate mating end or rod cap 136, the rod cap 136 being welded or otherwise attached to the end of the large diameter rod 132. However, in the alternative, the connection feature is formed directly on the large diameter rod 132, i.e., without a separate rod cap 136. For example, the end of the large diameter rod 132 may be directly threaded or machined to provide the shaft threaded portion 202 and the lug 204.

Formed on the inner wall of the sensor head tube 102 is a head tube threaded portion 208, the head tube threaded portion 208 mating with the threads of the shaft threaded portion 202. Between the head tube threaded portion 208 and the connection end of the sensor head tube 102, a lip 210 is formed. The lip 210 is sized such that when the large diameter stem 132 and the sensor head tube 102 are manually tightened together and result in the snap fit 200 (fig. 16), the sensor head tube 102 and the lip 210 can deform sufficiently enough to be pressed against the ledge 204. An O-ring 212 may be used to improve the snap fit. In particular, the fitting includes both threads and a snap fit, such that when the fitting is being torqued, the threads help to press the lip 210 against the ledge 204. It should be noted that although the illustrated embodiment has snap-fit features, other embodiments may not include snap-fit features.

Threaded joints risk rotation and back-out after installation. Using a threaded joint alone as part of an electromagnetic sensor head is challenging because the sensor must remain aligned after installation. Post-installation rotation reduces accuracy and may lead to accidental disassembly. The snap fit prevents axial movement rather than rotation. They are also weaker in bending. Combining the snap fit with the thread feature allows the meter to be assembled by hand rather than using a press; the joint only has to be rotated and the pieces pull themselves together. It also prevents flexing and increases the amount of torque required to remove the rod, thereby helping to prevent accidental disassembly. However, as noted, snap-fit features are not necessary to prevent disassembly or to prevent rotation.

The threaded feature in combination with the snap-fit feature locks the sensor head 100 to the large diameter rod 132 by preventing backout (i.e., reverse rotation). The threaded features (the shaft threaded portion 202 and the head tube threaded portion 208) pull the sensor head 100 onto the wand cap (the large diameter wand 132). As the parts are drawn together, the snap fit 200 features are engaged. Once the snap fit 200 has been engaged, it is not possible to easily remove the sensor head 100. Because the threads force the rotational movement to also have an axial movement, once the axial movement is locked, the sensor head 100 cannot rotate without additional torque. This prevents the joints from backing out and separating when in service, and also prevents rotation and misalignment of the sensor head 100 with respect to the shaft. Once the snap fit 200 is formed, a flat 220 or other mechanical key may be added to the top of the small diameter stem 134 that is aligned with the electrodes 105, 107, 109 so that the direction of rotation of the sensor assembly 101 is known after insertion into the flow tube 170.

While threaded joints alone have advantages over snap-fit joints, such as reduced bending and spreading of loads over a larger area, by combining the threaded features with snap-fit joints, a more rigid design and a stronger sensor head are generally achieved. In one example, both the snap feature and the thread feature may be produced on a lathe. This reduces tooling costs by eliminating the need for a mill (as with other anti-rotation features).

Fig. 17 shows a view of anchor 140, large diameter rod 132, and small diameter rod 134 in an uninstalled position within hot tap adapter 130. The large diameter pole 132 transitions to a small diameter pole 134 at a pole transition 133. The rod transition 133 is shown as tapering from the large diameter rod 132 to the small diameter rod 134. However, other transitions of sufficient strength may also be used. Anchors 140 are attached to both the large diameter rod 132 and the small diameter rod 134. Anchor 140 has a sufficient diameter to fit tightly within hot tap adapter 130. However, in one example, the anchor includes one or more holes within the anchor or a gap 142 around the anchor between it and the hot tap adapter 130 to equalize the pressure from the system flow 172 to the upper region 144. In one example, the gap 142 is advantageous because if the system flow 172 pressure is not equal to the upper region 144, the entire system pressure must be overcome in order to insert the rod. However, if the system pressure is allowed to be balancedThen less force is required. The size of the gap 142 should be adapted to allow pressure equalization during standard installation maintenance availability. The gap size may vary depending on the system design pressure. For example, for the same equilibration time, a larger gap may be required for a higher pressure system. As shown, the gap 142 area amounts to from about 0.180in²To about 0.136in²Which is about 16% of the total internal cross-sectional area of the example thermal tap adapter 130. The anchors 140 may include a friction reducing work piece, coating, or insert to reduce the sliding friction of the anchors 140 relative to the inner wall of the thermal tap adapter 130. For example, in an alternative embodiment, the anchor may comprise

Or acetal plastic sliders. However, other friction reducing coatings that do not contaminate the system may also be used. The thermal tap adapter 130 and the upper region 144 are sealed from the atmosphere by a top sealing cap 252 having an O-ring/seal 254.

Fig. 18 is a cross-sectional view along section line XVIII-XVIII of fig. 17. The large diameter pole 132 and anchor 140 are shown. The anchor 140 has a generally square profile with rounded corners 143. The rounded corners 143 ensure a close fit with little room for lateral displacement, the importance of which will be discussed below. Although space is shown at fillets 143 between anchors 140 and hot tap adapter 130, it is desirable to have no gaps. However, due to tolerances in machining, the gap is about 0.0015 inches to allow insertion. A gap 142 is provided to allow pressure equalization.

Fig. 19 is a cross-sectional view along section line XIX-XIX of fig. 17. A small diameter rod 134 and anchor 140 are shown. Fig. 19 illustrates the hydro-mechanical advantage obtained by using a mounting force for the small diameter rod 134 that opposes the system pressure on the anchor 140 and the large diameter rod 132. Each of the anchors 140 and the large diameter rods 132 has a larger surface area than the small diameter rods 134, that is, each of the anchors 140 has a larger cross-sectional surface area across each of their respective longitudinal axes than the small diameter rods 134. An increase in mechanical advantage is achieved according to pascal's law (or pascal's principle) due to the change in area from the small diameter rod 134 applying the installation force to the anchor 140 and the large diameter rod 132. This mechanical advantage reduces the force required to insert the sensor head tube and thus also reduces the complexity and expense of the insertion mechanism discussed further below. Conventional plug-in sensors (thermal tap sensors) trade off two factors in stem design: insertion force and flexural strength. The smaller the rod, the less force is required to mount the sensor. However, thin rods are subject to undesirable flexing, vibration, fatigue and breakage. However, the example disclosed embodiments allow for high strength (and small deflection) of large rods, along with low insertion force of small rods.

Fig. 20 and 21 show an example sensor assembly in two stages of installation. First, with valve 120 closed, the end of the hot tap adapter is connected to valve 120 at fitting 131. The joint 131 may be any known mechanical device to join pipes sufficient to withstand the pressure and mechanical stresses at the joint, including but not limited to threaded connections. Then, as discussed with reference to fig. 17-18, valve 120 is opened and system pressure is equalized across anchor 140. The direction of rotation is initially checked and adjusted by rotating the small diameter rod 134 before, after, or during pressure equalization, as will be discussed further below. After equilibration, the small diameter pole 134 is pushed toward the flow tube 170, which pushes the anchor 140, the large diameter pole 132, and the sensor head 100 into the flow tube 170. Following insertion, the direction of rotation can be further verified and adjusted.

In prior art thermal tap sensors, either the rod has a fixed diameter that is smaller than the inner diameter of its associated thermal tap adapter. That is, it does not fit tightly within its thermal tap adapter, allowing for mechanical flexing. Alternatively, the stem has the length of a large diameter hot tap adapter. In the small adapter configuration, the entire force of the system flow 172 acting perpendicular to the valve shaft 114 is transferred from the entire length 146 of the shaft to the top seal cap and results in a large moment arm that increases the torque on the stem and the top seal cap. These previous small stem configurations not only result in excessive stress to the stem and top seal cap, but also result in a higher likelihood of measurement inaccuracies due to deflection of the sensor. The inner diameter of the thermal tap adapter 130 is closely fitted in the example sensor assembly 101 to which the anchor 140 is currently applied. During installation, the anchor 140 is inserted with the large diameter rod 132 toward the flow tube 170, causing the anchor point or moment arm to dynamically displace toward the bottom of the flow tube 170. The anchor 140 has an insertion position closer to the tube 170 than in previous sensors. The anchor 140 acts as a fulcrum for the now reduced moment arm 148, which reduces mechanical deflection of the sensor head 100 as compared to previous sensors. Furthermore, as discussed above, the example sensor assembly also has a reduced insertion force compared to a fixed large rod configuration.

Fig. 22 and 23 show perspective and front schematic views of an example mechanical insertion device 260. A mechanical insertion device 260 may be used to manually insert the sensor head 100 into the bottom of the flow tube 170 and compress the spring 152. The mechanical insertion device 260 may be used for both clamping and insertion of the small diameter rod 134, and also for securing the rod against retraction after insertion. The mechanical insertion device 260 is shown to include an upper adjustment plate 154, the upper adjustment plate 154 helping to axially align the small diameter pole 134. The upper adjustment plate 154 is attached to the top seal cap 252 by threaded fasteners (e.g., bolts 264 that pass through 154 and are secured by threads cut in the top seal cap 252). In the alternative, the bolt 264 may be other threaded fasteners, such as a combination of a threaded rod and a wing nut or other type of nut. Alignment of upper adjustment plate 154 may be aided by alignment bar 266, which alignment bar 266 may also act as a stop to prevent over-insertion.

When tightened, the upper adjustment plate 154 applies a force to the spring 152, which spring 152 in turn applies a force to the collar 150 that is releasably tightened to the small diameter pole 134. This causes the rod to advance toward the flow tube 170. When the resilient feet 190 contact the bottom of the flow tube 170, the spring 152 will compress to prevent damage to the sensor head 100 while also applying continuous pressure. Once fully secured and aligned, the nut 156 may be tightened to secure the small diameter rod 134 in place. Nut 156 may be a compression nut and may include a pressure sleeve as is known in the art. The mechanical insertion device has an additional advantage over previous sensor assemblies in that axial movement along the shaft 114 is independent of rotational movement about the shaft 114. Thus, if sensor head 100 is not properly radially aligned, shaft 134 may be rotated during or after insertion using, for example, handle 268 (fig. 25). This allows for a proper sealing of the mechanically assisted heat 130 independent of the sensor head alignment.

An alternative mechanical insertion device 500 is shown in fig. 24, which mechanical insertion device 500 may replace the mechanical insertion device 260 in all of the above discussed embodiments, for example as shown in fig. 31. Referring back to fig. 24, the mechanical insertion device 500 utilizes a threaded pre-tension nut 504 as a single compression/rotation point, which threaded pre-tension nut 504 may, under certain conditions, improve the alignment of the retention rod 134 perpendicular to the flow tube 170 (fig. 1). The preload nut 504 is releasably engaged with a thermal tap housing 506, the thermal tap housing 506 being used to protect components inside the mechanical insertion device 500. The hot tap housing 506 is also adapted to have threads 505 on which the pre-tension nut 504 is advanced or retracted and also to provide a hard stop surface 514, as will be discussed below. A pre-tension nut set screw 508 may be provided to prevent movement between the pre-tension nut 504 and the thermal tap housing 506. A seal 516 is provided, the seal 516 may be, for example, an O-ring, and is similar in design and function to the seal 254 (fig. 17).

The mechanical insertion device 500 includes a main spring 510, e.g., a high tension spring, having a spring constant between about 1000in/lbs and about 1500in/lbs (e.g., about 1375 in/lbs). Main spring 510 provides a similar function as spring 152 (fig. 23). That is, main spring 510 applies a continuous pressure downward when compressed, so sensor head 100 (fig. 1) does not shift under high flow conditions or when the flow abruptly changes. The force of the main spring 510 is dispersed through the washer 512. A collar 520 located between the pre-tension nut 504 and the hot tap housing 506, or otherwise within the chamber defined by the pre-tension nut 504 and the hot tap housing 506, is releasably connected to the lever 134 and is used to transmit force between the main spring 510 and the lever 134. In one example, as shown, the collar 520 is releasably connected to the rod 134 using a collar screw 522 that tightens the collar 520 around the rod 134. Collar screw 522 may be any suitable fastener such as a hex notch fastener. A positioning spring 518 is included for maintaining the position of the collar 520 while securing the collar screw 522. A ferrule 503 and collet nut 502 may be used to secure the rod 134.

In fig. 25-27, rotational alignment about axis 114 is aided by a light emitting line (e.g., laser 310). The laser 310 is shown held in a laser mount 314, the laser mount 314 being mounted on the small diameter rod 134 and emitting a plane of light 316, the plane of light 316 appearing as a line on the flow tube 170 (fig. 26). This line extends a distance from the shaft 114 that allows the installer to be more precise in the axial rotation of the rod 134 than those of ordinary skill in the art who align the rod 134 with previously known means. For example, at a distance of two feet, a one degree rotation error is equivalent to about a half inch of deflection. Thus, if the light plane 316 extends as a line about four to five feet away from the valve 120, the one degree rotation error will be even more pronounced. In one example, the line will be several feet long (e.g., 18-36 inches), but will vary depending on the height of the sensor and the particular laser. The longer the wire, the more accurate the alignment can be. Small differences in angle will be multiplied by the length of the wire to be easily identified and corrected by turning the small diameter rod until the wire is straight. Marking a straight line along the center of the tube may further improve accuracy. The small diameter rod 134 will then be rotated until the laser line directly overlaps the marker line. This will further ensure accurate alignment.

Laser 310 may be powered and controlled by sensor assembly controller 300 through power and controller lines (not shown), or it may be battery operated and manually controlled. Prior to installation, the laser 310 and the laser mount 314 may each be rotationally aligned with the sensor head 100. To assist in the rotational alignment between sensor head tube 102, large diameter stem 132, small diameter stem 134, laser mount 314, and laser 310, keys such as flats, notches, etc. may be machined into each individual component prior to assembly of the sensor assembly. Such as flat 220 (fig. 15). And in one example, laser 310 and laser mount 314 are permanently mounted to small diameter rod 134.

The controller 300 is mounted on top of the small diameter rod 134. Each of the wires from the sensor head 100 travels up the interior of the large diameter shaft 132 and the small diameter shaft 134 and is electrically connected to the controller 300 inside the housing 302. The controller 300 may also be adapted to control other sensor assemblies. In such a configuration, wire assemblies from other sensor assemblies will also enter the housing 302. In an alternative embodiment, the controller 300 is installed in another home position and the wire is connected between the small diameter rod 134 and the controller 300.

Fig. 28 shows a plot of the magnetic field density looking down on the core 104 such that the axis 114 is out of the paper. Note that the darker areas of the figure represent higher magnetic field strengths. In previous sensor designs, the electrode wire was shielded from the strong magnetic field generated by the coil by drilling a hole in the center of the core (along axis 114) where the magnetic field was lowest and guiding the wire through the hole. Shielding is advantageous so that the magnetic field does not induce stray currents in the electrode wires. However, this practice is expensive for the machine and time consuming to install, especially in larger sized cores. In the present exemplary embodiment, the core 104 has channels 350 machined in the sides where no coils are wound on them. The design of the channel 350 and the core 104 results in a low magnetic field region 352. Alternatively, the electrode wire 112 may be routed along a channel 350 within a low magnetic field region 352. Spacers 116 (fig. 7) may be added to help retain the electrode wire 112 in the low magnetic field region 352. Making the core in this event is cheaper and easier to assemble than previous sensors.

Fig. 29A and 29B show electrical schematic diagrams of the controller 300 and the sensor head 100. A power supply (PSU 450 supplies power to a coil drive circuit 462 and a microcontroller unit (MCU) 455. MCU 455 includes an output electrically connected to a user input output (I/O)430 and a user interface control and configuration module 440, which module 440 may include buttons, selector switches, displays, indicators, digital and/or analog interfaces and alarms.mcu includes an oscillator 460(OSC) electrically connected to coil drive circuit 462. there is an H-bridge 463 and a current regulator 464 within coil driver circuit 462 to protect field coil 180. if the additional sensor assembly is being controlled by controller 300, an additional H-bridge and current regulator may be included if not already present within the selected H-bridge enclosure. H-bridge 463 excites field coil 180. H-bridge 463 is based on the current output at OSC field coil 180. permanent magnetization of core 104 is prevented using Alternating Current (AC), and also allows for the minimization of electrochemical and other effects at the electrode by filtering out DC voltage components, as discussed below.

Periodically, an electrical potential (voltage) is read at the electrodes 105, 107, and the voltage generated according to faraday's law is indicative of the velocity of the conductive fluid (e.g., water) through the magnetic field generated by the field coil 180. The electrodes 105, 107 may be electrically connected to the electrodes 106, 108, respectively, or may be independent. If they are separate, additional input channels may be included in the controller 300 up to an analog-to-digital converter (ADC)415, which may also have a multi-channel multiplexer feature. The voltage read at the electrodes 105, 107 is amplified at amplifier 410.

When configuring the measurement amplifier 410, the gain directly affects how much DC error can be removed from the input signal. The gain should be selected such that the amplifier 410 operates in its linear region, but not so high as to reduce the input range to a narrow margin.

Integrator 412 provides negative feedback at 414 to AC couple the signal. The resulting analog signal is then pre-filtered by a Low Pass Filter (LPF)416 to filter out high frequency noise and provide greater gain. The signal is then sent to BIAS 418 for final gain and proper offset to maximize the input resolution of the digital processing at ADC 415. The gain and filter stage LPF 416 is designed such that its bandwidth is significantly lower than the bandwidth of the digital filter 417, thereby ensuring that no aliasing of the higher frequency signals will interfere with the output of the digital filter 417. Further, the gain is adjusted to provide sufficient amplification to maximize the input range of the ADC. To avoid "clamping" of noise spikes that produce harmonic distortion of the signal, the output of the filter is biased to the half-supply point before being digitized.

Using AC through active circuitry eliminates the need to remove various stray DC potentials (e.g., electrochemical potentials at the electrodes). Rather than manually averaging several small points in the flow as done in previous sensors, analog integration of the voltage across the entire tube diameter allows infinite resolution sensing of the induced voltage without the need for weighting of the various readings. Reading a single voltage by the controller 300 greatly reduces controller and sensor complexity and cost. The exemplary embodiments also provide improved performance after bends or disturbances, which contributes to shorter straight-line routing requirements. For example, in a straight pipe, the velocity profile of the fluid flowing within the pipe is generally parabolic, and the depth of the average velocity vector is about 1/8 of the inner diameter. Therefore, previous sensors typically only measured 1/8 flow velocity at depth, and assumed that the flow velocity represents velocities at other depths. However, changes in the straightness of the pipe, such as bends or other connections, disrupt the parabolic velocity profile and thus reduce the accuracy of those previous meters (reading too high or too low depending on its position in the pipe). In contrast, the example flow sensor of the present application measures induced voltages across almost the entire inner diameter, such that those disturbances are sampled and included in the measurement results, and thus there are no strict pipe straight run requirements. Overall, this reduces system complexity and increases measurement accuracy.

Most previously known electromagnetic flow meters use a DC-coupled amplifier as a pre-stage, which results in the need for complex switching circuitry and precise timing techniques to process the input signal. This increases the non-linear behavior and the error. The present embodiment uses an AC-coupled preamplifier that allows for a linear intermediate amplifier and eliminates the need for complex switching circuitry and precise timing techniques. The AC coupling is achieved by applying negative feedback of the integrated input signal after the input stage of the measurement amplifier. The negative feedback eliminates DC offset while still providing high input impedance and high common mode rejection. AC coupling the signal while preserving the common mode rejection and high input impedance required for accurate sensing of the signal of the electromagnetic flow meter. This AC coupling scheme ensures that the signal leaving the first stage and pre-filtered (for anti-aliasing) and amplified will have a minimal amount of error contained in the signal, which increases the signal-to-noise ratio of the overall amplifier.

After amplification, the signal will be digitally rectified. The rectification and final filtering is accomplished digitally with a custom algorithm designed to provide a very stable output that still responds quickly to the input, increasing accuracy and performance, and filtering with an adaptive filtering algorithm, resulting in a more linear, accurate and accurate electromagnetic flow meter. The controller 455 precisely rectifies the signal and converts the square wave (produced by the alternating magnetic field) into a DC value proportional to the flow. The controller 455 is configured to "hop" if the input changes, providing the benefits of a tight filter (stable output) and a loose filter (faster response). Further, the controller 455 automatically zeroes itself by looking at two subsequent and opposite coil pulses, thus eliminating fabrication and installation steps and improving installation efficiency.

Once the signal has been converted from an analog signal to a digital signal at the ADC 415, the controller 455 automatically zeroes the signal, converts the alternating signal to a DC level proportional to flow and applies final filtering. To accomplish this, the controller 455 monitors the input and output of the signal and looks for a change in the input equal to the current percentage. If the input "jumps," the output follows, which in turn increases the responsiveness of the device. That is, the controller 455 looks at two consecutive pulses of opposite sign and uses this information to rectify the signal, largely filtering out noise and accommodating large input variations.

The signal is then output by the MCU as the resulting flow velocity, volume or mass flow depending on the configuration at 420.

Referring to fig. 30, a method 600 of installing the sensor assembly 101 (fig. 1) including the mechanical insertion device 500 (fig. 24) will be discussed. At step 602, a counterclockwise half turn or more is applied to the collet nut 502, collar screw 522, and set screw 508 to ensure that the rod 134, pretension nut 504, and collar 520 can move freely. It should be noted that depending on the thread configuration and thread direction, more or fewer turns may be required for a particular configuration. At step 604, the sensor head 101 slides out of the hot tap adapter 130 by several inches to ensure it is free to move. If not, additional adjustments are made to the collet nut 502 and the collar screw 522 to ensure that they are not tightened and then retried. At step 606, the sensor head 101 is fully retracted within the thermal tap adapter 130. At step 608, the tube threads of the thermal tap adapter 130 are covered in a suitable tube sealant, e.g., a tube tape. At step 608, with valve 120 held closed, the threaded end of the hot tap adapter 130 is inserted into valve 120 and secured, for example, by turning clockwise with a suitable tool. At step 610, the valve 120 is opened and checked for leaks at the threaded joint. If there is any leakage, valve 120 is closed and additional torque is applied to hot tap adapter 130, and then opened and checked again for leakage.

At step 612, the pre-tension nut 504 is fully inserted into the thermal tap housing 506 by rotating the pre-tension nut 504 all the way clockwise (assuming right-handed threads). In one configuration, the lip 522 of the pre-tension nut 504 should be flush with the top of the thermal tap housing 506 and there are no visible threads, and the pre-tension nut 504 should not be turned any further. At step 614, the laser 310 (fig. 25) is turned on (if included) and the sensor assembly 101 is aligned with the flow tube 170, with the laser pointing toward the center of the tube in the expected downstream direction. At step 616, the pretension nut 504 is turned counter clockwise 1 and 1/4 turns and the pretension collar is checked to ensure that it can move inside the housing. At step 618, sensor head 100 is slowly inserted into the tube using handle 268 (fig. 25). At this step, if the rod 134 is pushed in, it should spring up slightly on its positioning spring. At step 620, additional checks may be performed on the laser alignment with corrections, if necessary. At step 622, collar screw 522 is tightened using a fastener accessed through window 530 (fig. 31) or an opening in heat tap housing 506 while maintaining a downward force on handle 268. If necessary during this step, collar 520 may need to be rotated within heat tap housing 506 to gain access to the head of collar screw 522. At step 624, the pre-tension nut 504 is rotated (clockwise, assuming right-handed threads) into the thermal tap housing 506 until it bottoms out at the hard stop 514. This action pre-loads the main spring 510. The lip 524 of the pretension nut 504 should be flush with the top of the housing 506 without visible threads and the pretension nut 504 should not be rotated any further. At step 626, the collet nut 502 is tightened. While the collet nut 502 is tightened, alignment should be maintained by using the handle 268 as an aid to counteract torque. At step 628, the laser 310 is turned off and the set screw 508 on the side of the thermal tap housing 506 is tightened. At step 630, an electrical connection is made to the controller 300 (FIG. 29A).

It should be understood that the above description is only illustrative of the present invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

Claimed as novel and desired to be protected by the patent letters are:

1. a sensor assembly, the sensor assembly comprising:

a rod;

a sensor head coupled to the stem, the sensor head including at least one top electrode and at least one bottom electrode; and

a field coil configured to emit an alternating magnetic field when excited with an alternating current,

wherein the at least one top electrode and the at least one bottom electrode are configured to measure a voltage potential of a conductive fluid when the sensor head is inserted within a flow tube having an inner circumferential surface.

2. The sensor assembly of claim 1, wherein said at least one top electrode is proximate a first portion of said inner circumferential surface of said flow tube when said sensor assembly is inserted within said flow tube, and said at least one bottom electrode is proximate a second portion of said inner circumferential surface of said flow tube when said sensor assembly is inserted within said flow tube, and said first portion and said second portion are diametrically opposed.

3. The sensor assembly of claim 1, wherein the sensor head is attached to the stem via a threaded connection.

4. The sensor assembly of claim 1, wherein said sensor head is attached to a shaft, and said shaft has a large diameter portion and a small diameter portion, said large diameter portion being closer to said sensor head than said small diameter portion.

5. The sensor assembly of claim 4, wherein the rod includes an anchor fixedly connected to the large diameter portion and the small diameter portion, the anchor having a larger cross-sectional surface area across each of respective longitudinal axes of the anchor and the small diameter portion than the small diameter portion.

6. The sensor assembly of claim 5 wherein said anchor having a larger cross-sectional surface area than said small diameter portion provides a hydro-mechanical advantage of the force exerted on said small diameter portion.

7. The sensor assembly of claim 5, wherein the sensor assembly further comprises a thermal tap adapter, and an outer diameter of the anchor is smaller than an inner diameter of the thermal tap adapter.

8. The sensor assembly of claim 7, further comprising a gap between the anchor and the thermal tap adapter to allow pressure equalization across the anchor.

9. The sensor assembly of claim 7, wherein the anchor assembly is sized to fit closely within the thermal tap adapter to minimize lateral deflection of the sensor head when installed in a flow tube.

10. The sensor assembly of claim 1, wherein the sensor head comprises a core and the field coil is wrapped around first and second sides of the core.

11. The sensor assembly of claim 10, wherein the core includes channels along third and fourth sides of the core, and the channels are parallel to a central longitudinal axis of the core.

12. A sensor assembly as claimed in claim 10, in which the sensor head is moulded and/or overmoulded over the core and/or electrode.

13. The sensor assembly of claim 11, wherein said sensor head comprises at least one electrode wire within said channel.

14. The sensor assembly of claim 11, wherein a portion of the channel is in a lower magnetic field region when the field coil is excited.

15. The sensor assembly of claim 13, wherein sensor head includes at least one spacer in said channel such that said electrode wire is between said spacer and said central longitudinal axis of said core.

16. The sensor assembly of claim 1, further comprising a mechanical insertion device comprising a top sealing cap, an upper conditioning plate.

17. The sensor assembly of claim 16, wherein the stem passes through the top seal cap and the upper conditioning plate, and further comprising a spring and a collar each at least partially circumferentially surrounding the stem between the top seal cap and the upper conditioning plate.

18. The sensor assembly of claim 14, wherein the stem is rotatable before, during, and after insertion of the sensor head into the flow tube and independently of a suitably sealed thermal tap adapter.

19. The sensor assembly of claim 14, further comprising a light emitting wire attached to the rod and configured to emit a wire onto an outer surface of the tube during and/or after insertion of the sensor assembly into the tube.

20. The sensor assembly of claim 1, further comprising a controller, wherein the controller is adapted to generate and alternate current field coil current sources, measure voltages across the at least one top electrode and the at least one bottom electrode, and amplify and filter the resulting signals.

21. The sensor assembly of claim 20, wherein the controller is further configured to monitor the input and output of the signal and look at two consecutive pulses of opposite sign and use this information to rectify the signal, filter out noise and accommodate large input variations.

22. The sensor assembly of claim 1, further comprising a mechanical insertion device comprising a pre-tensioned nut and a thermal tap housing.

23. The sensor assembly of claim 22, further comprising a collar and a positioning spring.

24. The sensor assembly of claim 23, further comprising a main spring.

25. A method of inserting a sensor assembly into a flow tube, the method comprising:

securing a pre-tightened nut within the hot tap housing;

applying a force to at least one handle connected to a rod to insert the sensor assembly within the flow tube;

securing a collar to the stem, wherein the collar is between the preload nut and the hot tap housing;

tightening the pre-tension nut into the thermal tap housing until the pre-tension nut bottoms out at a hard stop.

26. The method of claim 25, wherein tightening the pre-tightening nut 504 into the heat tap housing until the pre-tightening nut bottoms out at a hard stop of the heat tap housing further comprises compressing a main spring.

27. The method of claim 25, wherein securing a collar to the rod further comprises holding the collar in place with a retaining spring.

28. The method of claim 25, wherein the hard stop is part of the thermal tap housing.

29. The method of claim 25, further comprising tightening a collet nut around the rod.

30. The method of claim 25, further comprising aligning the sensor assembly with the flow tube using a light emitting wire.

Claimed as novel and desired to be protected by the patent letters are:

Claims

1. a magnetic plug-in meter, comprising:

a sensor head cylinder having a textured front surface; and

at least two electrodes.

2. The plug-in meter of claim 1 further comprising a field coil configured to emit an alternating magnetic field when excited with an alternating current.

3. The plug-in meter of claim 1, wherein the textured front surface is an upstream surface.

4. The plug-in meter of claim 1, wherein the textured front surface is at least one of an abrasive, an impregnated abrasive, a deposited abrasive, and/or an abrasive layer on a substrate.

5. The plug-in meter of claim 4, wherein the textured front surface is sandpaper.

6. The insertion meter of claim 1, wherein the textured front surface has a higher roughness than a material forming the sensor head tube.

7. The plug-in meter of claim 1, wherein the textured front surface comprises at least one groove.

8. The plug-in meter of claim 7, wherein the textured front surface comprises two grooves extending along a longitudinal axis of the sensor head cylinder.

9. The plug-in meter of claim 1, wherein the textured front surface comprises dimples.

10. The plug-in meter of claim 9, wherein the plurality of dimples are equally spaced from one another.

11. The plug-in meter of claim 10, wherein the plurality of dimples form a pattern in which three meters of the plurality of meters form an equilateral triangle.

12. The plug-in meter of claim 9, wherein the textured front surface comprises a plurality of rows of dimples.

13. The plug-in meter of claim 12, wherein the textured front surface comprises from about 3 columns of dimples to about 7 columns of dimples.

14. The plug-in meter of claim 7, wherein the textured front surface comprises dimples.

15. The insertion meter of claim 1, wherein the textured front surface is adapted to alter a boundary layer of fluid flowing through a sensor head tube as compared to the same sensor head tube that does not contain the textured front surface.

16. The insertion meter of claim 1, wherein the textured front surface is adapted to move a separation point of fluid flowing through the sensor head tube toward the front surface as compared to an identical sensor head tube that does not contain the textured front surface.

17. The plug-in meter of claim 1, wherein the textured surface is a surface profile.

18. A method of measuring flow, the method comprising,

providing a magnetic insertion meter comprising a sensor head cylinder having a textured front surface and at least two electrodes; and

measuring an output of the electrode.

19. The method of claim 18, wherein the textured front surface is at least one of an abrasive, an impregnated abrasive, a deposited abrasive, and/or an abrasive layer on a substrate.

20. The method of claim 18, wherein the textured front surface comprises at least one of dimples and/or grooves.